Firefox Extension requires disabling full browser security
The Firefox Extension only works for detecting successful login if the
privacy.firstparty.isolate=false. This is one of the primary security mechanisms in Firefox and disabling this affects the security of the entire browser for all browsing. As a result this change is a non-starter for any user that actually knows what the setting is.
No other standard Firefox add-ins seem to need this critical security function disabled to support login and retention of login, including ones like Dynalist that have almost identical clipper functionality. Please fix the Firefox Extension so it, and the service, are usable for Firefox users.